Eating fish raw at home: the UK rules

Fish eaten raw or lightly cured in the UK has to be frozen first, and that surprises most people. Freezing is the step that kills parasite larvae, and it is a legal requirement for food businesses under retained Regulation 853/2004. The Food Standards Agency advises home cooks to do the same. There are exceptions, mainly for some farmed fish, and there are separate rules for live shellfish. This page explains what the rules are, why they exist and how to prepare raw fish safely at home.

Does fish have to be frozen before it is eaten raw?

For food businesses in the UK, yes, with limited exceptions. Fishery products intended to be eaten raw or almost raw must be frozen throughout to -20C or below for at least 24 hours, or to -35C or below for at least 15 hours. The same requirement covers cold-smoked fish where the flesh does not reach 60C, and marinated, salted or lightly cured products where the process is not strong enough to kill parasite larvae on its own. Ceviche, tartare, carpaccio and gravlax all sit inside this.

Households are not regulated, but the Food Standards Agency gives home cooks the same advice with an adjustment for domestic equipment. A home freezer typically runs at around -18C and holds temperature less reliably than a commercial blast freezer, so the FSA advice is to freeze fish for at least four days before eating it raw. Longer at a warmer temperature is doing the same job more slowly.

Why does freezing make raw fish safe?

Because of parasites. Marine fish commonly carry the larvae of nematode worms, principally Anisakis, which live in the gut and can migrate into the flesh after the fish dies. Cooking kills them. Chilling does not. Freezing at the temperatures above does.

Two honest caveats. First, freezing kills parasites and does nothing to bacteria or viruses, which is why cold chain, clean hands and a clean board still matter for raw preparation. Second, gutting fish promptly after catch reduces migration into the flesh but does not remove the requirement.

Which fish are exempt from the freezing rule?

Farmed fish can be exempt where it has been reared from embryos in facilities where the parasite risk is controlled and fed on feed that cannot contain live parasites, and where the business holds records to show it. This exemption is the reason farmed salmon and farmed trout are commonly served raw without a separate freezing step. It applies to the specific farmed supply chain rather than to salmon as a species, so wild salmon is not covered.

Some other products fall outside the requirement, including fishery products that will be heat treated in a way that kills larvae, and certain species and preparations where the risk has been assessed as negligible. If you are cooking at home and you are unsure which side of the line something falls, freezing it is the simple answer and costs you nothing but time.

Is there such a thing as a grade of fish for eating raw?

No. There is no legal grade, no official certification and no defined standard behind the terms retailers use to suggest one. Any phrasing along those lines is a seller's description rather than a regulated claim.

What actually makes fish suitable to eat raw is a short list you can check yourself: it was handled cold and quickly, it is in excellent condition, it has been frozen correctly for the required time and temperature and it has been kept clean since. Ask a seller those four questions and the answers tell you far more than any label does.

How do I prepare raw fish safely at home?

• Start with fish in excellent condition. Clear domed eyes, deep red gills, springy flesh and a clean smell of salt water. The checks are in how to tell if fish is fresh.
• Buy it whole and have it filleted if you can. A whole fish shows you the signals a fillet hides, and a fishmonger will fillet, skin and pin-bone it for you.
• Freeze it yourself. Wrap tightly in thin, flat portions so the cold reaches the centre quickly, and give it at least four days in a home freezer.
• Thaw it in the fridge on a rack over a tray, covered, and use it the same day.
• Keep everything cold and clean. A chilled board, a clean sharp knife, dry hands and no contact with anything raw that is not fish.
• Slice against the grain with one long stroke. Sawing tears the flesh and turns it woolly.
• Serve it cold and eat it promptly. Raw fish is not something to leave standing on a table.

What about oysters and other raw shellfish?

Different rules, different risk. Live bivalves such as oysters, mussels and clams are eaten raw or lightly cooked and are not frozen first. They are controlled instead at source: they must come from classified harvesting areas and, depending on that classification, be purified before sale. They arrive alive and should stay alive until you open them. Discard any that are open and do not close when tapped, and any that smell wrong.

The risks with raw shellfish are bacterial and viral rather than parasitic, and freezing would not address them. The Food Standards Agency advises that people who are pregnant, older, immunocompromised or living with liver disease avoid raw shellfish altogether. Our primer on native and rock oysters covers the seasons, and how to shuck an oyster covers the technique.

Can you eat raw fish when pregnant?

NHS guidance is that raw fish dishes are acceptable in pregnancy where the fish has been frozen first, and that raw shellfish should be avoided. There is separate guidance limiting oily fish and some large predatory species. We have summarised the current position in fish that is safe in pregnancy, and the NHS pages are the source to follow over anything a shop tells you.

Ask us before you plan it

We run a counter on Barnes High Street and we cut everything by hand. If you are planning something raw or cured, tell us at the counter or when you call, so we can talk you through what is in good condition, fillet and pin-bone it for you and be straight with you about what has and has not been frozen. Our page on fresh or frozen fish explains why that question is worth asking every time you buy. If you are new to buying at a counter, this is what to ask.

This page is general information about UK food safety guidance and is not medical advice. For personal health questions, follow NHS guidance or speak to a healthcare professional.